Ozone Catalytic Oxidation of HCHO in Air over MnOx at Room Temperature

The complete oxidation of HCHO in air with O3 over MnOx catalysts at room temperature was studied. The MnOx catalysts were prepared by a redox method. The catalysts showed amorphous patterns in X-ray diffraction characterization. Formaldehyde in simulated air containing 137 mg/m3 HCHO with 56% relative humidity (RH, 25 °C) was totally oxidized to CO2 by 642 mg/m3 O3 over the MnOx catalysts at GHSV (gas hourly space velocity) = 2 × 105 h−1. The formaldehyde conversion and CO2 selectivity were maintained at ∼ 100% during 150 min time-on-stream. The effect of the molar ratio of O3 to HCHO was also investigated. At a O3 to HCHO molar ratio of 2:3, which was significantly lower than the stoichiometric ratio, a CO2 selectivity of 100% was still achieved. No byproduct was detected during HCHO oxidation with O3 over the MnOx catalysts using an online Fourier transform infrared spectrometer.

摘要采用氧化还原法制备了 MnOx 催化剂, Ｘ射线衍射结果表明其主要为无定形结构. 在甲醛和臭氧浓度分别为 137 和 642 mg/m3, 相对湿度为 56% (25 oC), GHSV 为 2 × 105 h条件下, MnOx 催化剂上 O3 可将甲醛全部氧化为 CO2, 反应 150 min 内甲醛转化率和 CO2 选择性一直保持在–100%. 另外, 当臭氧与甲醛的摩尔比约为 2:3, 即显著低于化学计量比时, CO2 选择性仍可达–100%. 采用傅里叶变换红外光谱仪在线分析了甲醛氧化反应产物, 未检测到任何副产物, 从而确认了 MnOx 催化剂上 O3 对甲醛的完全氧化.

Ozone catalytic oxidation of HCHO in air over MnOx at room temperature with 100% CO2 selectivity was achieved, even with a O3/HCHO molar ratio significantly lower than the stoichiometric ratio.Figure optionsDownload as PowerPoint slide